Throttle body and method of manufacturing the same

ABSTRACT

A throttle body includes a resin body ( 3 ) defining a bore ( 7 ) through which intake air flows, and a valve body ( 60 ) having a shaft part ( 20 ) rotatably supported by the body ( 3 ) via a pair of bearing members ( 24 ) and a resin valve part ( 4 ) for opening and closing the bore ( 7 ). End faces ( 67 ) of the valve part ( 4 ) slidably contacting with end faces ( 69 ) of the bearing members ( 24 ). The end faces ( 67 ) and ( 69 ) of at least one of the valve part ( 4 ) and the bearing members ( 24 ) slidably contacting with each other are formed to have a radius ( 69   r ) equal to or larger than a radius ( 68   r ) of paths of rotation ( 68 ) of radially outer ends ( 67   a ) of the end faces ( 67 ) of the valve part ( 4 ).

TECHNICAL FIELD

The present invention relates to a throttle body for controlling anintake air amount of an internal combustion engine and a method ofmanufacturing the same.

BACKGROUND ART

A conventional throttle body is equipped with a resin main body forminga bore through which intake air flows, a metal shaft part rotatablysupported by the main body through the intermediation of a pair of metalbearing members, and a valve body having a resin valve part for openingand closing the bore. The main body is molded with the valve bodyinserted together with the pair of bearing members. In ordinary throttlebodies, a moving amount of the valve body in a thrust direction (axialdirection) is regulated through sliding contact of end faces of thevalve part with end faces of the bearing members. Patent Document 1discloses a throttle body manufacturing method in which the main body ismolded with the valve body inserted.

Patent Document 1: JP 2001-212846 A DISCLOSURE OF THE INVENTION Problemto be Solved by the Invention

In the above-mentioned conventional throttle body, the end faces of thebearing members are formed in a radius smaller than a radius of thepaths of rotation of the radially outer ends of the end faces of thevalve part. As a result, the radially outer ends of the end faces of thevalve part extrude beyond the end faces of the bearing members. Thus, asa result of rotation caused by the opening/closing of the valve part,the radially outer ends of the valve part come into sliding contact withan inner wall surface or so-called bore wall surface of the main bodyopposed thereto. Thus, resin-to-resin sliding contact occurs between thevalve part and the main body, and therefore, there has been apossibility that the wear of the resin increases, and an operationproperty of the valve body is impaired.

It is an object of the present invention to provide a throttle body anda method of manufacturing the same which can improve the operationproperty of the valve body.

Means for Solving the Problem

The above-mentioned object can be achieved by a throttle body and amethod of manufacturing the same, the gist of which are defined in theclaims.

That is, a first aspect of the invention is a throttle body including:

a resin main body defining a bore through which intake air flows; and

a valve body having a shaft part rotatably supported by the main bodyvia a pair of bearing members and a resin valve part for opening andclosing the bore of the main body, end faces of the valve part slidablycontacting with end faces of the bearing members, wherein:

the end faces of at least one of the valve part and the bearing membersslidably contacting with each other are formed as end faces of a goodsliding property, and

the end faces of the bearing members slidably contacting with the endfaces of the bearing members are formed to have a radius equal to orlarger than a radius of paths of rotation of radially outer ends of theend faces of the valve part.

According to the first aspect of the invention, constructed as describedabove, the bore of the main body is opened and closed by the valve partrotating with the shaft part of the valve body, so that an amount ofintake air flowing through the bore, that is, an intake air amount, iscontrolled.

Further, a moving amount of the valve body in a thrust direction isregulated through sliding contact of the end faces of the valve partwith the end faces of the bearing members.

The end faces of at least one of the valve part and the bearing membersslidably contacting with each other are formed as end faces of a goodsliding property, so that it is possible to reduce the frictionalresistance of the end faces of the valve part with respect to the endfaces of the bearing members.

Further, the end faces of the bearing members are formed to have aradius equal to or larger than the radius of the paths of rotation ofthe radially outer ends of the end faces of the valve part, so that theentire end faces of the valve part can slidably contact with the endfaces of the bearing members, and it is possible to avoid slidingcontact of the valve part with the bore wall surface of the main body.

Thus, due to a synergistic effect of reduction in the frictionalresistance of the end faces of the valve part with respect to the endfaces of the bearing members and avoidance of sliding contact of thevalve part with the bore wall surface of the main body, it is possibleto improve an operation property of the valve body.

A second aspect of the invention is a throttle body according to thefirst aspect of the invention, in which the bearing members are made ofa material having a good sliding property.

According to the second aspect of the invention, constructed asdescribed above, the bearing members are made of the material having agood sliding property, so that it is possible to reduce frictionalresistance between the end faces of the valve part and the end faces ofthe bearing members.

A third aspect of the invention is a throttle body according to thefirst aspect of the invention, in which slide layers having a goodsliding property are provided on the end faces of the valve part, whichslidably contact with the end faces of the bearing members.

According to the third aspect of the invention, constructed as describedabove, the slide layers having a good sliding property are provided onthe end faces of the bearing members, which slidably contact with theend faces of the valve part, so that it is possible to reduce thefrictional resistance between the end faces of the valve part and theend faces of the bearing members.

A fourth aspect of the invention is a throttle body according to any oneof the first to third aspects of the inventions, in which the slidelayers having a good sliding property are provided on the end faces ofthe valve part, which slidably contact with the end faces of the bearingmembers.

According to the fourth aspect of the invention, constructed asdescribed above, the slide layers having a good sliding property areprovided on the end faces of the valve part, so that it is possible toreduce the frictional resistance between the end faces of the valve partand the end faces of the bearing members.

A fifth aspect of the invention is a throttle body according to any oneof the first to fourth aspects of the inventions, in which slide layershaving a good sliding property are provided on outer peripheral surfacesof support shaft portions of the shaft part, which are rotatablysupported by the bearing members.

According to the fifth aspect of the invention, constructed as describedabove, the slide layers having a good sliding property are provided onthe outer peripheral surfaces of the support shaft portions of the shaftpart, so that it is possible to reduce frictional resistance betweeninner peripheral surfaces of shaft holes of the bearing members and theouter peripheral surfaces of the support shaft portions of the shaftpart.

A sixth aspect of the invention relates to a throttle body according toany one of the first to fifth aspects of the inventions, in which slidelayers having a good sliding property are provided on inner peripheralsurfaces of shaft holes of the bearing members, which are rotatablysupporting the shaft part.

According to the sixth aspect of the invention, constructed as describedabove, the slide layers having a good sliding property are provided onthe inner peripheral surfaces of the shaft holes of the bearing members,so that it is possible to reduce the frictional resistance between theinner peripheral surfaces of the shaft holes of the bearing members andthe outer peripheral surfaces of the support shaft portions of the shaftpart.

A seventh aspect of the invention is a throttle body including:

a resin main body defining a bore through which intake air flows; and

a valve body having a shaft part rotatably supported by the main bodyvia a pair of bearing members and a resin valve part for opening andclosing the bore of the main body, end faces of the valve part slidablycontacting with end faces of the bearing members, wherein:

the bearing members are made of metal,

the shaft part is made of resin, and

slide layers having a good sliding property are provided on outerperipheral surfaces of support shaft portions of the shaft partrotatably supported by the bearing members.

According to the seventh aspect of the invention, constructed asdescribed above, the bore of the main body is opened and closed by thevalve part rotating with the shaft part of the valve body, so that theamount of intake air flowing through the bore, that is, the intake airamount, is controlled.

Further, the moving amount of the valve body in the thrust direction isregulated through sliding contact of the end faces of the valve partwith the end faces of the bearing members.

Here, the bearing members are made of metal, the shaft part is made ofresin, and the slide layers having a good sliding property are providedon the outer peripheral surfaces of the support shaft portions of theshaft part. Therefore, it is possible to reduce the frictionalresistance of the support shaft portions of the resin shaft part withrespect to the metal bearing members. Further, by making the shaft partof resin, it is possible to abolish the shaft part made of metal, sothat it is possible to achieve a reduction in cost and weight. Further,in this case, by molding the shaft part integrally with the valve body,it is possible to achieve a further reduction in cost.

An eighth aspect of the invention is a throttle body including:

a resin main body defining a bore through which intake air flows; and

a valve body having a shaft part rotatably supported by the main bodyvia a pair of bearing members and a resin valve part for opening andclosing the bore of the main body, end faces of the valve part slidablycontacting with end faces of the bearing member, wherein:

the bearing members are made of metal,

the shaft part is made of resin, and

slide layers having a good sliding property are provided on the endfaces of the valve part, which slidably contact with the end faces ofthe bearing members.

According to the eighth aspect of the invention, constructed asdescribed above, the bore of the main body is opened and closed by thevalve part rotating with the shaft part of the valve body, so that theamount of intake air flowing through the bore, that is, the intake airamount, is controlled.

Further, the moving amount of the valve body in the thrust direction isregulated through sliding contact of the end faces of the valve partwith the end faces of the bearing members.

Here, the bearing members are made of resin, the shaft part is made ofmetal, and the slide layers having a good sliding property are providedon the end faces of the valve part, which slidably contact with the endfaces of the bearing members. Therefore, it is possible to reduce thefrictional resistance of the end faces of the valve part made of resinwith respect to the end faces of the bearing members made of resin.Further, by making the bearing members of resin, it is possible toachieve a reduction in cost and weight. Further, in this case, bymolding the bearing members integrally with the main body, it ispossible to achieve a further reduction in cost.

A ninth aspect of the invention is a throttle body including:

a resin main body defining a bore through which intake air flows; and

a valve body having a shaft part rotatably supported by the main bodyvia a pair of bearing members and a resin valve part for opening andclosing the bore of the main body, end faces of the valve part slidablycontacting with end faces of the bearing member, wherein:

the bearing members are made of metal,

the shaft part is made of resin, and

slide layers having a good sliding property are provided on the endfaces of the bearing members, which slidably contact with the end facesof the valve part.

According to the ninth aspect of the invention, constructed as describedabove the bore of the main body is opened and closed by the valve partrotating with the shaft part of the valve body, so that the amount ofintake air flowing through the bore, that is, the intake air amount, iscontrolled.

Further, the moving amount of the valve body in the thrust direction isregulated through sliding contact of the end faces of the valve partwith the end faces of the bearing members.

Here, the bearing members are made of resin, the shaft part is made ofmetal, and the slide layers having a good sliding property are providedon the end faces of the bearing members, which slidably contact with theend faces of the valve part. Therefore, it is possible to reduce thefrictional resistance of the end faces of the valve part made of resinwith respect to the end faces of the bearing members made of resin.Further, by making the bearing members of resin, it is possible toachieve a reduction in cost and weight. Further, in this case, bymolding the bearing members integrally with the main body, it ispossible to achieve a further reduction in cost.

A tenth aspect of the invention is a throttle body including:

a resin main body defining a bore through which intake air flows; and

a valve body having a shaft part rotatably supported by the main bodyvia a pair of bearing members and a resin valve part for opening andclosing the bore of the main body, end faces of the valve part slidablycontacting with end faces of the bearing members, wherein:

the bearing members and the shaft part are made of resin, and

slide layers having a good sliding property are provided on the endfaces of the valve part, which slidably contact with the end faces ofthe bearing members, and on outer peripheral surfaces of support shaftportions of the shaft part, which are rotatably supported by the bearingmembers.

According to the tenth aspect of the invention, constructed as describedabove, the bore of the main body is opened and closed by the valve partrotating with the shaft part of the valve body, so that the amount ofintake air flowing through the bore, that is, the intake air amount, iscontrolled.

Further, the moving amount of the valve body in the thrust direction isregulated through sliding contact of the end faces of the valve partwith the end faces of the bearing members.

Here, the bearing members and the shaft part are made of resin, andslide layers having a good sliding property are provided on the endfaces of the valve part, which slidably contact with the end faces ofthe bearing members, and on the outer peripheral surfaces of the supportshaft portions of the shaft part, which are rotatably supported by thebearing members. Therefore, it is possible to reduce the frictionalresistance of the end faces of the valve part made of resin with respectto the end faces of the bearing members, which are made of resin, andthe frictional resistance of the support shaft portions of the resinshaft part with respect to the bearing members. Further, by making thebearing. members and the shaft part of resin, it is possible to achievea reduction in cost and weight. Further, in this case, by molding thebearing members integrally with the main body, it is possible to achievea further reduction in cost. Further, by molding the shaft partintegrally with the valve body, it is possible to achieve a furtherreduction in cost

An eleventh aspect of the invention is a throttle body including:

a resin main body defining a bore through which intake air flows; and

a valve body having a shaft part rotatably supported by the main bodyvia a pair of bearing members and a resin valve for opening and closingthe bore of the main body, end faces of the valve part slidablycontacting with end faces of the bearing members, wherein:

the bearing members are made of resin,

the shaft part is made of metal, and

slide layers having a good sliding property are provided on the endfaces of the bearing members, which slidably contact with the end facesof the valve part, and on inner peripheral surfaces of shaft holes ofthe bearing members, which rotatably support the shaft part.

According to the eleventh aspect of the invention, constructed asdescribed above, the bore of the main body is opened and closed by thevalve part rotating with the shaft part of the valve body, so that theamount of intake air flowing through the bore, that is, the intake airamount, is controlled.

Further, the moving amount of the valve body in the thrust direction isregulated through sliding. contact of the end faces of the valve partwith the end faces of the bearing members.

Here, the bearing members are made of resin, the shaft part is made ofmetal, and the slide layers having a good sliding property are providedon the end faces of the bearing members, which slidably contact with theend faces of the valve part, and on the inner peripheral surfaces of theshaft holes of the bearing members, which rotatably support the shaftpart. Therefore, it is possible to reduce the frictional resistance ofthe end faces of the valve part formed of a resin with respect to theend faces of the bearing members formed of a resin and the frictionalresistance of the support shaft portions of the resin shaft part withrespect to the bearing members. Further, by making the bearing membersof resin, it is possible to achieve a reduction in cost and weight.Further, in this case, by molding the bearing members integrally withthe main body, it is possible to achieve a further reduction in cost.

A twelfth aspect of the invention is a throttle body including:

a resin main body defining a bore through which intake air flows; and

a valve body having a shaft part rotatably supported by the main bodyvia a pair of bearing members and a resin valve part for opening andclosing the bore of the main body, end faces of the valve part slidablycontacting with end faces of the bearing members,

wherein clearances between the end faces of the valve part and the endfaces of the bearing members are adjusted through axial movement of thebearing members.

According to the twelfth aspect of the invention, constructed asdescribed above, the bore of the main body is opened and closed by thevalve part rotating with the shaft part of the valve body, so that theamount of intake air flowing through the bore, that is, the intake airamount, is controlled.

Further, the moving amount of the valve body in the thrust direction isregulated through sliding contact of the end faces of the valve partwith the end faces of the bearing members.

By moving the bearing members in the axial direction, the clearancesbetween the end faces of the valve part and the end faces of the bearingmembers are adjusted to a predetermined amount. Thus, it is possible toimprove the operation property of the valve body. It is desirable thatthe clearances between the end faces of the valve part and the end facesof the bearing members are those making it possible to reduce a leakageamount of intake air (hereinafter referred to as “air leakage amount”)when the valve body is fully closed, while improving the operationproperty of the valve body.

A thirteenth aspect of the invention is a throttle body including:

a resin main body defining a bore through which intake air flows; and

a valve body having a shaft part rotatably supported by the main bodyvia a pair of bearing members and a resin valve part for opening andclosing the bore of the main body, end faces of the valve part slidablycontact with end faces of the bearing members,

wherein, between the end faces of the valve part and the end faces ofthe bearing members, spacer means for setting clearances between the endfaces to a predetermined. amount are provided.

According to the thirteenth aspect of the invention, constructed asdescribed above, the bore of the main body is opened and closed by thevalve part rotating with the shaft part of the valve body, so that theamount of intake air flowing through the bore, that is, the intake airamount, is controlled.

Further, the moving amount of the valve body in the thrust direction isregulated through sliding contact of the end faces of the valve partwith the end faces of the bearing members.

By virtue of the spacer means provided between the end faces of thevalve part and the end faces of the bearing members, it is possible toset the clearances between the end faces to a predetermined amount.Thus, it is possible to improve the operation property of the valvebody. It is desirable that the clearances between the end faces of thevalve part and the end faces of the bearing members are those making itpossible to reduce the air leakage amount when the valve body is fullyclosed, while improving the operation property of the valve body. Thespacer means may be of any type as long as they are capable of settingthe clearances between the end faces of the valve part and the end facesof the bearing members to a predetermined amount; they may be removedafter the setting of the clearances between the end faces, or may not beremoved if they undergo resilient deformation after the setting of theclearances between the end faces.

A fourteenth aspect of the invention is a method of manufacturing athrottle body, the throttle body including:

a resin main body defining a bore through which intake air flows; and

a valve body having a shaft part rotatably supported by the main bodyvia a pair of bearing members and a resin valve part for opening andclosing the bore of the main body, end faces of the valve part slidablycontacting with end faces of the bearing members,

the method of manufacturing the throttle body including adjustingclearances between the end faces of the valve part and the end faces ofthe bearing members through axial movement of the bearing members aftermolding the main body.

According to the fourteenth aspect of the invention, constructed asdescribed above, it is possible to manufacture a throttle body that canprovide the same effects as those of the twelfth aspect of theinvention.

A fifteenth aspect of the invention is a method of manufacturing athrottle body, the throttle body including:

a resin main body defining a bore through which intake air flows; and

a valve body having a shaft part rotatably supported by the main bodyvia a pair of bearing members and a resin valve part for opening andclosing the bore of the main body, end faces of the valve part slidablycontacting with end faces of the bearing members,

the method of manufacturing the throttle body including settingclearances between the end faces of the valve part and the end faces ofthe bearing members to a predetermined amount by spacer means when oneof the valve part and the main body is molded, with the other of theminserted together with the bearing members.

According to the fifteenth aspect of the invention, constructed asdescribed above, it is possible to manufacture a throttle body that canprovide the same effects as those of the thirteenth aspect of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 A front view of a throttle body according to Embodiment 1.

FIG. 2 A bottom view of the throttle body.

FIG. 3 A sectional view taken along the arrow line III-III in FIG. 2.

FIG. 4 A sectional view taken along the arrow line IV-IV in FIG. 1.

FIG. 5 A left side view of a main body with a cover body removedtherefrom.

FIG. 6 An enlarged view of a portion VI in FIG. 3.

FIG. 7 An explanatory view illustrating a relationship between a valvepart and bearing sleeves.

FIG. 8 A sectional view of a primary portion of Embodiment 2.

FIG. 9 A sectional view of a primary portion of Embodiment 3.

FIG. 10 A front sectional view of a throttle body according toEmbodiment 4.

FIG. 11 A sectional view of a primary portion at a time of molding amain body.

FIG. 12 An end view of a portion around a bearing sleeve at the time ofmolding the main body.

FIG. 13 A sectional view of a primary portion after movement foradjustment of the bearing sleeve.

FIG. 14 A sectional view of the portion around the bearing sleeve afterthe movement for adjustment of the bearing sleeve.

FIG. 15 A sectional view of a body molding die.

FIG. 16 A perspective view of a bearing-sleeve pivotal die.

FIG. 17 A sectional view of a primary portion of Embodiment 5.

FIG. 18 A perspective view of a spacer member.

FIG. 19 A sectional view of a primary portion of Modification 1.

FIG. 20 A perspective view of a gage member.

FIG. 21 A sectional view of a primary portion of Modification 2.

FIG. 22 A side view of a valve body.

FIG. 23 A sectional view of a primary portion of Modification 3.

FIG. 24 A sectional view of a primary portion after removal of aprojecting portion.

FIG. 25 A sectional view of a primary portion of Modification 4.

BEST MODES FOR CARRYING OUT THE INVENTION

Next, best modes for carrying out the invention will be described withreference to embodiments.

Embodiment 1

Embodiment 1 will be described. This embodiment will be described inrelation to a so-called electronic control type throttle body in which avalve body is opening/closing-controlled by a motor. FIG. 1 is a frontview of a throttle body, FIG. 2 is a bottom view of the throttle body,FIG. 3 is a sectional view taken along the arrow line III-III in FIG. 2,FIG. 4 is a sectional view taken along the arrow line IV-IV in FIG. 1,FIG. 5 is a left side view of a main body with a cover body removedtherefrom, FIG. 6 is an enlarged view of a portion VI in FIG. 3, andFIG. 7 is an explanatory view illustrating the relationship between avalve member and a bearing sleeve.

As shown in FIG. 4, a throttle body 2 is provided with a resin main body3 and a resin valve member 4 (see FIGS. 1 and 3). The main body 3 andthe valve member 4 are both formed by injection molding processes.

With the main body 3, a bore wall portion 5 and a motor housing portion6 are integrally molded (see FIGS. 3 and 4).

The bore wall portion 5 is formed substantially as a hollow cylinderhaving a bore 7 extending in the right and left directions as seen inFIG. 4. The bore wall portion 5 has a straight cylindrical inlet-sidetubular connecting portion 8 extending continuously from the right tothe left in FIG. 5, a conical tubular portion 9 formed as a conical tubewhose diameter is gradually decreased, a primary tubular portion 10formed as a straight cylinder, an inverted conical tubular portion 11formed as an inverted conical tube whose diameter gradually increases,and an outlet-side tubular connecting portion 12 formed as a straightcylinder. The inner wall surface of the bore 7 of the bore wall portion5 composed of the tubular portions 8, 9, 10, 11, and 12 will begenerally referred to as “bore wall surface” (labeled with numeral 13).

As shown in FIG. 7, on the inner peripheral surface of the primarytubular portion 10, an annular-strip-like sealing surface 16 is formedand is surface-to-surface contact with a sealing surface 15 at the outerperipheral end surface of the valve member 4 (hereinafter described).The sealing surfaces 15 of the valve member 4 will be referred to as“valve-side sealing surfaces”, and the sealing surface 16 of the mainbody 3 will be referred to as “body-side sealing surface”.

As shown in FIG. 2, a flange portion 18 for fastening protrudessubstantially in a rectangular-plate-like fashion and is connected withthe outer peripheral surface of the opening end portion on the side ofthe outlet-side tubular connecting portion of the bore wall portion 5.Metal bushes 19 are provided at four corners of the flange portion 18for fastening (see FIG. 1). Fastening bolts (not shown) for fastening anintake manifold, which is arranged on the downstream side of the mainbody 3, to the flange portion 18 for fastening can be passed through thebushes 19.

An air cleaner (not shown) arranged on the upstream side of the mainbody 3 is fitted into the inlet-side tubular connecting portion 8 of thebore wall portion 5 for communication therewith. The intake manifold(not shown), which is arranged on the downstream side of the main body3, is fastened to the flange portion 18 for fastening by fasteningbolts/nuts for communication with the outlet-side tubular connectingportion 12 of the bore wall portion 5. In this way, communication isestablished between the bore wall portion 5 of the main body 3, the aircleaner, and the intake manifold, so that intake air from the aircleaner flows to the intake manifold through the bore 7 in the bore wallportion 5.

As shown in FIG. 3, a metal throttle shaft 20 is disposed in the borewall portion 5 and extends radially across the bore 7 (in right and leftdirections in FIG. 3). Right and left support shaft portions 21 formedat both ends of the throttle shaft 20 are rotatably supported by a pairof right and left bearing sleeves 24 inserted into a pair of right andleft bearing boss portions 22. formed integrally with the bore wallportion 5. The shaft support portions 21 are formed to have a largeouter diameter than that of a shaft body 20 a of the throttle shaft 20.The bearing sleeves 24 are formed of a pair of metal bushes arrangedsymmetrically on the right and left sides. The outer peripheral portionsof the bearing sleeves 24 are respectively surrounded by the bearingboss portions 22 and are placed in position with respect to the axialdirection. The bearing sleeves 24 will be described later in more detail

In FIG. 3, the right end portion of the throttle shaft 20 isaccommodated in the right-side bearing boss portion 22. A plug 26 ismounted to the right-side bearing portion 22 by press-fitting or likemeans for sealing the opening end surface thereof.

The left end portion of the throttle shaft 20 extends through theleft-side bearing boss portion 22 and protrudes to the left. A rubbersealing material 27 is fitted into the left-side bearing boss portion 22from the opening side thereof (left side in FIG. 3). The innerperipheral portion of the sealing material 27 is slidably fitted into acircumferential annular groove (not labeled with reference numeral)formed in the outer peripheral surface of the throttle shaft 20. Due tothe sealing material 27, air leakage from a gear housing space 29(described below) into the bore 7, and air leakage from the bore 7 intothe gear housing space 29 are prevented.

As shown in FIG. 4, the substantially disc-like valve member 4 is formedintegrally with the throttle shaft 20 by an insert molding process. Thevalve member 4 rotates together with the throttle shaft 20 to open/closethe bore 7 in the bore wall portion 5 in order to control the amount ofintake air flowing through the bore 7. The solid line 4 in FIG. 4indicates the closed state of the valve member 4. Rotating clockwise inFIG. 4 from the closed state (i.e., in direction of arrow O in FIG. 4),sets the valve member 4 to the open state (indicated by dash-double-dotlines 4 in FIG. 4). Rotating counterclockwise in FIG. 4 (i.e., indirection of arrow S in FIG. 4) from the open state sets the valvemember 4 to the closed state (see solid line 4 in FIG. 4).

As shown in FIG. 3, a throttle gear 30 formed, for example, of a resinsector gear, is integrally provided at the left end portion of thethrottle shaft 20, which protrudes from the left-side bearing bossportion 22 (see FIG. 5).

Further, between the throttle gear 30 and the side surface of the mainbody 3 facing the end surface of the throttle gear 30, a back spring 32is provided to be positioned on the rotational axis L of the throttleshaft 20. The back spring 32 holds the throttle gear 30 constantly andresiliently in a position (hereinafter referred to as opener openingposition) opened by a predetermined angle from the fully open position.

As shown in FIG. 3, the motor housing portion 6 of the main body 3 issubstantially formed as a bottomed cylinder parallel to the rotationalaxis L of the throttle shaft 20 and open to the left in FIG. 3. Thedrive motor 33 constituted, for example, by a DC drive motor isaccommodated in the motor housing portion 6. A mounting flange 35 isprovided on a motor housing 34 defining an outer contour of the drivemotor 33 and is fixed to the main body 3 by fixing means (e.g., screws35 a) (see FIG. 5).

Further, a motor pinion 37 formed, for example, of a resin (see FIG. 5)is integrally formed with the protruding end of a motor shaft 36, whichprotrudes to the left in FIG. 3 from the mounting flange 35 of the drivemotor 33.

As shown in FIG. 3, between the main body 3 and a cover body 40 closingthe open end surface thereof (left-side open end surface in FIG. 3), ahollow counter shaft 38 is provided and extends parallel to therotational axis L of the throttle shaft 20. The counter shaft 38 is, forexample, a metal hollow cylinder and is fitted into and positionedbetween protruding shaft portions 41 and 42 respectively protruding fromopposing end surfaces of the main body 3 and the cover body 40.

A counter gear 39 formed, for example, of a resin is rotatably supportedby the counter shaft 38. As shown in FIG. 5, the counter gear 39 has alarge diameter gear part 43 and a small diameter gear part 44 which areof different gear diameters. The large diameter gear part 43 is in meshwith the motor pinion 37, and the small diameter gear part 44 is in meshwith the throttle gear 30.

A reduction gear mechanism 45 is constituted by the throttle gear 30,the motor pinion 37, and the counter gear 39. The reduction gearmechanism 45 is accommodated in the gear housing space 29 formed betweenthe main body 3 and the cover body 40 (see FIG. 3).

The cover body 40, which is made, for example, of resin is joined to oneside surface (left side surface in FIG. 3) of the main body 3. As ajoining means for joining the cover body 40 to the main body 3, it ispossible to adopt a snap-fit means, a clip means, a screw fasteningmeans, welding, etc. Further, between the main body 3 and the cover body40, an O-ring 46 for maintaining hermeticity of an interior isinterposed if necessary.

As shown in FIG. 1, a connector portion 48 is formed integrally with thecover body 40. An external connector (not shown) electrically isconnected to a control device 52 (see FIG. 2) and can be connected tothe connector portion 48. Terminals 51 a to 51 f are arranged in theconnector portion 48. The terminals 51 a to 51 f are electricallyconnected to the drive motor 33 (see FIG. 3) and a throttle positionsensor 50 described below (see FIG. 3).

The drive motor 33 (see FIG. 3) is drive-controlled by the controldevice 52, such as an engine control unit, or an ECU of an automobile(see FIG. 2), in response to an accelerator signal related to gas pedaldepressing amount, a traction control signal, a constant-speed travelingsignal, and an idle speed control signal.

The drive force of the motor shaft 36 of the drive motor 33 istransmitted from the motor pinion 37 to the throttle shaft 20 throughthe counter gear 39 and the throttle gear 30. This causes the valvemember 4, which is integrated with the throttle shaft 20, to be rotated,with the result that the bore 7 is opened or closed.

As shown in FIG. 3, the throttle gear 30 is integrally provided with aring-like yoke 53 made of a magnetic material and positioned coaxiallywith the rotational axis L of the throttle shaft 20. The innerperipheral surface of the yoke 53 is integrated with a pair of magnets54 and 55 generating magnetic fields. The magnets 54 and 55 are formed,for example, of ferrite magnets, and are parallel-magnetized so that themagnetic lines of force generated between them, that is, the magneticfields, are parallel to each other, generating substantially parallelmagnetic fields in the space within the yoke 53.

On the inner side surface of the cover body 40, the throttle positionsensor 50, which is a rotation angle sensor equipped with a sensor IC 56with a built-in magnetoresistive element, is positioned. The throttleposition sensor 50 is positioned on the rotational axis L of thethrottle shaft 20 and between the magnets 54 and 55 at a predeterminedinterval. The sensor IC 56 of throttle position sensor 50 computes theoutput from the magnetoresistive element and outputs an output signalcorresponding to the direction of the magnetic field to the controldevice 52, so that it is possible to detect the direction of themagnetic field without depending on the intensity of the magnetic field.

With the above-mentioned throttle body 2 (see FIGS. 1 through 5), whenthe engine is started, the drive motor 33 is drive-controlled by thecontrol device 52. As noted above, the valve body 60 is therebyopened/closed through the reduction gear mechanism 45, with the resultthat the amount of intake air flowing through the bore 7 of the mainbody 3 is controlled.

As the throttle shaft 20 rotates, the yoke 53 and the magnets 54 and 55rotate together with the throttle gear 30, so that the direction of themagnetic field across the sensor IC 56 of the throttle position sensor50 varies in response to the rotation angle, and the output signal ofthe sensor 50 varies. The control device 52 thereby calculates therotation angle of the throttle shaft 20, that is, the throttle openingof the valve member 4, in response to the output signal of the throttleposition sensor 50.

The control device 52 (see FIG. 2) controls so-called controlparameters, such as fuel injection control, correction control on theopening of the valve member 4, and automatic transmission control basedon the throttle opening output from the sensor IC 56 of the throttleposition sensor 50 (see FIG. 3) and detected according to the directionof the magnetic field as magnetic physical amount of the pair of magnets54 and 55, vehicle speed detected by a vehicle speed sensor (not shown),engine RPM according to a crank angle sensor, and detection signals fromsensors such as a gas pedal sensor, an O₂ sensor, and an air flow meter.

As shown in FIG. 4, the resin of the valve member 4, integrally moldedon the throttle shaft 20, surrounds the periphery of the throttle shaft20. At the center of the throttle shaft 20 corresponding to the centerof the valve member 4, a through-hole 58 is formed to extend radially,and the resin has been flown into the through-hole 58. The valve body 60is constituted by the throttle shaft 20 and the valve member 4 (seeFIGS. 7 and 8).

The valve member 4 corresponds to the “valve part” in the presentspecification. The throttle shaft 20 corresponds to the “shaft part” inthe present specification. While in this embodiment the valve body 60 isformed by integrating the throttle shaft 20 and the valve member 4, itis also possible to form the shaft part and the valve part as anintegral unit of a resin (e.g., integral molding), thus forming a resinvalve part in the form of a single component.

The valve member 4 has a shaft cover portion 61, a bridging portion 62,plate-like portions 63, and rib portions 65; The shaft cover portion 61is formed in a substantially cylindrical configuration so as to surroundthe throttle shaft 20. The bridging portion 62 extends between opposingsurfaces at the center of the shaft cover portion 61 so as to extendthrough the through-hole 58 of the throttle shaft 20. The plate-likeportions 63 are formed of a pair of semi-circular portions and protrudein opposite directions from the shaft cover portion 61 so as toconstitute a single disc (see FIG. 3). The valve-side sealing surfaces15 are formed at the outer peripheral end surfaces of the plate-likeportions 63 (see FIG. 7).

As shown in FIG. 7, the valve-side sealing surfaces 15 of the plate-likeportions 63 are formed in point symmetry with respect to the axis L, andare formed as tapered surfaces whose outer diameter gradually increasesfrom the closed side toward the open side with respect to the thicknessdirection. Further, the valve-side sealing surfaces 15 are formed at thetime of molding the valve member 4, and are in surface-to-surfacecontact with the sealing surface 16 of the main body 3. As stated above,on the bore wall surface 13 of the primary tubular portion 10 of themain body 3, the body-side sealing surface 16 is formed and is insurface-to-surface contact with the valve-side sealing surfaces 15 ofthe valve member 4 (see FIG. 7).

The bearing contact portions 64 expand annularly from both end portionsof the shaft cover portion 61 (FIG. 6 only shows the right end portion),and extend over both plate-like portions 63.

The rib portions 65 are continuous with the shaft cover portion 61 andprotrude in a plural number from the front and back surfaces of theplate-like portions 63 at predetermined intervals (see FIG. 1). Ridgesof the rib portions 65 extend from near free ends of the plate-likeportions 63 tangentially with respect to the outer peripheral surface ofthe shaft cover portion 61 (see FIG. 7).

The support shaft portions 21 of the throttle shaft 20 and the bearingcontact portions 64 of the valve member 4 are formed so as to be spacedapart from each other by a predetermined interval, with thesmall-diameter shaft body 20 a being exposed in a groove-like fashionbetween the support shaft portions 21 and the bearing contact portions64 (see FIG. 6). Further, except for the valve-side sealing surfaces 15,the valve member 4 is formed symmetrically with respect to both sidesand both surfaces thereof.

Next, a method of manufacturing the above-mentioned throttle body 2 willbe described. As methods of manufacturing the throttle body 2, amanufacturing method 1 and a manufacturing method 2, described below,are available.

Manufacturing Method 1 for the Throttle Body 2

A manufacturing method 1 for the throttle body 2 includes a process ofmolding the valve body 60 and a process of molding the main body 3.

In the process for molding the valve body 60, the valve member 4 ismolded by a resin injection molding process using a valve molding die(mold). In this process, the throttle shaft 20 is inserted into thevalve molding die, and then resin is injected into a mold space, thatis, so-called cavity in conformity with the configuration of the valvemember 4, so that the valve 60 is molded with the valve member 4integrated with the throttle shaft 20. Since the valve molding die usedin this process is of a well-known construction, a description thereofwill be omitted.

Next, in the process for molding the main body 3, the main body 3 ismolded by a resin injection molding process using a body molding die(mold). In this process, the valve body 60 molded in the previousprocess, the bearing sleeves 24, etc. are inserted, and then resin isinjected into a mold space, that is, so-called cavity corresponding tothe configuration of the main body 3, so that the main body 3 is moldedwith the valve body 60 assembled (see FIG. 5). Further, the resin isfilled along the valve-side sealing surfaces 15 of the valve member 4,so that the body-side sealing surface 16 in conformity with thevalve-side sealing surfaces 15 is formed in the main body 3. The bodymolding die used in this process will be described below.

Manufacturing Method 2 for the Throttle Body 2

Manufacturing method 2 for the throttle body 2 includes a process ofmolding the main body 3 and a process of molding the valve body 60.

First, in the process of molding the main body 3, the main body 3 ismolded by a resin injection molding process using a body molding die(mold). At that time, the bearing sleeves 24 is inserted, and then theresin is injected into a molding space, that is, so-called cavity inconformity with the configuration of the main body 3, so that a bodysubassembly in which the main body 3 is integrated with the bearingsleeves 24. The body molding die used in this process is of a well-knownconstruction, and therefore, a description thereof will be omitted.

Next, in the process of molding the valve body 60, the valve member 4 ismolded by a resin injection molding process using a valve molding die(mold). At that time, the body subassembly molded in the previousprocess and the throttle shaft 20 are inserted into the valve moldingdie, and then resin is injected into a molding space or so-called cavityin conformity with the configuration of the valve member 4, so that thevalve member 4 having the body subassembly incorporated therein andintegrated with the throttle shaft 20 is molded. Further, the resin isfilled along the body-side sealing surface 16 of the main body 3, sothat the valve-side sealing surfaces 15 in conformity with the body-sidesealing surface 16 are formed in the valve member 4. The valve moldingdie used in this process is of a well-known construction, and therefore,a description thereof will be omitted.

The plug 26, the sealing material 27, the back spring 32, the drivemotor 33, the reduction gear mechanism 45, the cover body 40, etc. areassembled to the throttle body 2 molded by the manufacturing method 1 orthe manufacturing method 2 described above, so that the throttle body 2is completed (see FIG. 3).

As the resin material of the main body 3 and the valve member 4described above, it is possible to use a composite material using asynthetic resin as the base material (matrix). Examples of the syntheticresin base material that can be adopted include polyester type resinssuch as polyethylene terephthalate and polybutylene terephthalate,polyolefin type resins such as polyethylene and polypropylene, polyamidetype resins such as polyamide 6, polyamide 66, and aromatic polyamide,general-purpose resins such as ABS, polycarbonate, and polyacetal, superengineering plastics such as a polyacetal resin, polyphenylene sulfide,polyether sulfone, polyetherether ketone, polyether nitrile, andpolyether imide, thermosetting resins such as a phenol resin, an epoxyresin, and an unsaturated polyester resin, and synthetic resins such asa silicone resin and a teflon (registered trademark) resin.

The above-mentioned composite material includes a fibrous material and afiller material. Examples of such materials that can be adopted includefibers such as glass fiber, carbon fiber, ceramics fiber, cellulosefiber, vinylon fiber, brass fiber, and aramide fiber, calcium carbonate,zinc oxide, titanium oxide, alumina, silica, magnesium hydroxide, talc,calcium silicate, mica, glass, carbon, graphite, thermosetting resinpowder, and cashew dust. In some cases, it is possible to mix flameretardant, ultraviolet inhibitor, antioxidant, lubricant, etc. with thecomposite material

Next, the construction of a primary portion of this embodiment will bedescribed. As shown in FIG. 3, the valve member 4 and the bearingsleeves 24 are formed symmetrically, so the following description willcenter on right-hand side portions of those, and a description of lefthand side portions of those will be omitted.

As shown in FIG. 6, the moving amount of the valve member 4 in thethrust direction (horizontal direction in FIG. 6) is regulated throughsliding contact between the opposing end faces of the valve member 4 andthe bearing sleeves 24. The end faces 67 of the bearing contact portions64 of the valve member 4 facing end faces 69 of the bearing sleeves 24will be referred to as the “slide faces of the valve member 4,valve-side slide faces”, etc., and the end faces 69 in sliding contactwith the valve-side slide faces 67 will be referred to as the “slidefaces of the bearing sleeves 24, bearing-side slide faces 69”, etc. Thevalve-side slide faces 67 and the bearing-side slide faces 69 are formedby planes orthogonal to the rotation axis L of the throttle shaft 20.Between the valve-side slide faces 67 and the bearing-side slide faces69, there are secured predetermined clearances or so-called gaps inorder to achieve an improvement in terms of the operation propertyregarding the opening and closing of the valve body 60. In thisspecification, the “clearances between the valve-side slide faces 67 andthe bearing-side slide faces 69” refer to the clearances between theslide faces 67, 69 when the valve member 4 is situated coaxially insidethe bore 7. The bearing sleeves 24 correspond to the “bearing members”in this specification.

Each bearing sleeve 24 has a cylindrical tube body 70 and a flangeportion 71 annularly expanding from the outer periphery of a valve-sideend portion of the tube body 70. The bearing sleeves 24 are formed ofdry bearings made of material having a good sliding property. Examplesof the material having a good sliding property include metal materials,such as a copper-type sintered material and a SUS material.

The outer peripheral portion of each bearing sleeve 24 including theflange portion 71 is surrounded by a bearing boss portion 22 of the mainbody 3.

The slide face 69 of each bearing sleeve 24 is formed by thecorresponding end face of the tube body 70 including the flange portion71.

Further, the slide face 69 of each bearing sleeve 24 is formed to have aradius 69 r which is equal to or larger than a radius 68 r of a path ofrotation 68 of the radially outer end (indicated by reference symbol 67a in FIG. 7) of each slide face 67 of the valve member 4 (see FIG. 7).With this arrangement, the slide faces 67 of the valve member 4 canentirely slidably contact with the slide faces 69 of the bearing sleeves24.

FIG. 7 also shows a radius 69R of the bearing-side slide faces 69 of aconventional example. Conventionally, the bearing-side slide faces 69are formed to have the radius 69R which is smaller than the radius 68 rof the path of rotation 68, so that the radially outer end portions ofthe valve-side slide faces 67 extend beyond the bearing-side slide faces69. Thus, the radially outer end portions of the valve-side slide faces67 slidably contact with the bore wall surface 13, which is the opposingwall surface of the main body 3, resulting in resin-to-resin slidingcontact between the valve member 4 and the main body 3.

With throttle body 2 described above, the bore 7 of the main body 3 isopened and closed by the valve member 4 rotating with the throttle shaft20 of the valve body 60, so that the amount of intake air flowingthrough the bore 7, that is, the intake air amount, is controlled.

Further, the moving amount of the valve member 4 in the thrust direction(axial direction) is regulated through the sliding contact of the endfaces 67 of the valve member 4 with the end faces 69 of the bearingsleeves 24.

The bearing sleeves 24 are formed of a metal material having a goodsliding property, and the end faces 69 of the bearing sleeves 24 areformed as end faces (slide faces) of a good sliding property, so that itis possible to reduce the frictional resistance of the end faces 67 ofthe valve member 4 against the end faces 69 of the bearing sleeves 24.

Further, the end faces 69 of the bearing sleeves 24 are formed to havethe radius 69 r, which is equal to or larger than the radius 68 r of thepaths of rotation 68 of the radially outer ends 67 a of the end faces 67of the valve member 4, so that the end faces 67 of the valve member 4can entirely slidably contact with the end faces 69 of the bearingsleeves 24. Therefore, it is possible to avoid sliding contact of thevalve member 4 with the bore wall surface 13 of the main body 3.

Thus, by the synergistic effect of the reduction in the frictionalresistance of the end faces 67 of the valve member 4 against the endfaces 69 of the bearing sleeves 24 and the avoidance of sliding contactof the valve member 4 with the bore wall surface 13 of the main body 3,it is possible to improve the operation property of the valve member 4.

An experiment conducted by the present applicant for comparison betweena conventional product and a product according to this embodiment interms of a wear amount of the end faces 67 of the valve member 4 and theend faces 69 of the bearing sleeves 24 showed that, as compared with theconventional example, this embodiment exhibits reduction in the wearamount to approximately ⅙.

Further, since the bearing sleeves 24 themselves are formed of a metalmaterial having a good sliding property, it is possible to reduce thefrictional resistance between the end faces 67 of the valve member 4 andthe end faces 69 of the bearing sleeves 24.

The same effects as described above can be obtained by using, instead ofa metal material having a good sliding property, a resin material havinga good sliding property, such as a polyphenylene sulfide resin (PPS), asthe material of the bearing sleeves 24 themselves.

Further, the same effects can be obtained by forming slide layers havinga good sliding property on the end faces 69 of the bearing sleeve 24.The slide layers having a good sliding property can be formed, forexample, by plasma ion implantation films, fluororesin coating films,etc. In such a case, as the bearing sleeves 24, those made of metal,resin, etc. may be used.

The same effects as described above can be obtained by forming slidelayers having a good sliding property on the end faces 67 of the valvemember 4. The slide layers having a good sliding property can be formed,for example, by plasma ion implantation films, fluororesin coatingfilms, etc.

Further, it is possible to provide slide layers having a good slidingproperty on the outer peripheral surfaces of the support shaft portions21 of the throttle shaft 20, which are rotatably supported by thebearing sleeves 24. With this construction, it is possible to reduce thefrictional resistance between the inner peripheral surfaces of the shaftholes of the bearing sleeves 24 and the outer peripheral surfaces of thesupport shaft portions 21 of the throttle shaft 20.

Further, it is possible to provide slide layers having a good slidingproperty on the inner peripheral surfaces of the shaft holes of thebearing sleeves, which rotatably support the support shaft portions 21of the throttle shaft 20. With this construction, it is possible toreduce the frictional resistance between the inner peripheral surfacesof the shaft holes of the bearing sleeves 24 and the outer peripheralsurfaces of the support shaft portions 21 of the throttle shaft 20.

Further, it is possible to make the throttle shaft 20 of the aboveembodiment of resin, and to provide slide layers having a good slidingproperty on the outer peripheral surfaces of the support shaft portions21 of the throttle shaft 20, which are rotatably supported by thebearing sleeves 24. With this construction, it possible to reduce thefrictional resistance of the support shaft portions 21 of the resinthrottle shaft 20 against the metal bearing sleeves 24. Further, bymaking the throttle shaft 20 of resin, it is possible to abolish themetal throttle shaft, so it is possible to achieve a reduction in costand weight. In such a case, by molding the throttle shaft 20 integrallywith the valve member 4, it is possible to achieve a further reductionin cost. The throttle shaft 20 can be made of polyphenylene sulfideresin (PPS) or the like, which has a good sliding property.

Further, it is possible to make the bearing sleeves 24 of the aboveembodiment of resin, and to provide slide layers having a good slidingproperty on the end faces 67 of the valve member 4, which slidablycontact with the end faces 69 of the bearing sleeves 24. With thisconstruction, it possible to reduce the frictional resistance of the endfaces 67 of the resin valve member 4 against the end faces 24 of theresin bearing sleeves. Further, by making the bearing sleeves 24 ofresin, it is possible to abolish the metal bearing sleeves, so that itis possible to achieve a reduction in cost and weight. Further, in sucha case, by molding the bearing sleeves 24 integrally with the bearingboss portions 22 of the main body 3, it is possible to achieve a furtherreduction in cost. The bearing sleeves 24 can be made of polyphenylenesulfide resin (PPS) or the like, which has a good sliding property.

Further, it is possible to make the bearing sleeves 24 of the aboveembodiment of resin, and to provide slide layer of a good slidingproperty on the end faces 69 of the bearing sleeves 24, which slidablycontact with the end faces 67 of the valve member 4. With thisconstruction, it possible to reduce the frictional resistance of the endfaces 67 of the resin valve member 4 against the end faces 24 of theresin bearing sleeves. Further, by making the bearing sleeves 24 ofresin, it is possible to abolish the metal bearing sleeves, so that itis possible to achieve a reduction in cost and weight. In such a case,by molding the bearing sleeves 24 integrally with the bearing bossportions 22 of the main body 3, it is possible to achieve a furtherreduction in cost. The bearing sleeves 24 can be made of polyphenylenesulfide resin (PPS) or the like, which has a good sliding property.

Further, it is possible to make the bearing sleeves 24 and the throttleshaft 20 of the above embodiment of resin, and to provide slide layershaving a good sliding property on the end faces 67 of the valve member4, which slidably contact with the end faces 69 of the bearing sleeves24, and on the outer peripheral surfaces of the support shaft portions21 of the throttle shaft 20, which are rotatably supported by thebearing sleeves 24. With this construction, it is possible to reduce thefrictional resistance of the end faces 67 of the resin valve member 4against the end faces 69 of the resin bearing sleeves 24 and thefrictional resistance of the support shaft portions 21 of the resinthrottle shaft 20 against the bearing sleeves 24. Further, by making thebearing sleeves 24 and the throttle shaft 20 of resin, it is possible toabolish the bearing sleeves and the throttle shaft that are made ofmetal, so that it is possible to achieve a reduction in cost and weight.In such a case, by molding the bearing sleeves 24 integrally with thebearing boss portions 22 of the main body 3, it is possible to achieve afurther reduction in cost. Further, by molding the throttle shaft 20integrally with the valve body 60, it is possible to achieve a furtherreduction in cost. The bearing sleeves 24 and the throttle shaft 20 canbe made of polyphenylene sulfide resin (PPS) or the like, which has agood sliding property.

Further, it is possible to make the bearing sleeves 24 of the aboveembodiment of resin, and to provide slide layers having a good slidingproperty on the end faces 69 of the bearing sleeves 24, which slidablycontact with the end faces 67 of the valve member 4, and on the innerperipheral surfaces of the shaft holes of the bearing members, whichrotatably support the throttle shaft 20. With this construction, itpossible to reduce the frictional resistance of the end faces 67 of theresin valve member 4 against the end faces 69 of the resin bearingsleeves 24 and the frictional resistance of the support shaft portions21 of the resin throttle shaft 20 against the bearing sleeves 24.Further, since the bearing sleeves 24 are made of resin, it is possibleto abolish the metal bearing sleeves, so that it is possible to achievea reduction in cost and weight. In such a case, by molding the bearingsleeves 24 integrally with the bearing boss portions 22 of the main body3, it is possible to achieve a further reduction in cost. The bearingsleeves 24 can be made of polyphenylene sulfide resin (PPS) or the like,which has a good sliding property.

Embodiment 2

Embodiment 2 will be described. This embodiment is a partialmodification of Embodiment 1, so that the following description will bemade to the modified portions, and a redundant description will not bemade. Also, for the following embodiments, the description will be madeto the modified portions, and a redundant description will not be made.

As shown in FIG. 8, in this embodiment, annular stepped portions 73 areformed on the inner periphery of the end faces 69 of the bearing sleeves24. The bearing contact portions 64 of the valve member 4 are fittedinto the stepped portions 73.

According to this embodiment, since the bearing contact portions 64 ofthe valve member 4 are fitted into the stepped portions 73 of the endfaces 69 of the bearing sleeves 24, clearances 72 between the end facesof the bearing sleeves 24 and the valve member 4 exhibit a labyrinthstructure. As a result, when the valve body 60 is fully closed, the flowof intake air through the clearances 72 between the end faces of thebearing sleeves 24 and the valve member 4 is hindered. Thus, it ispossible to reduce the air leakage amount when the valve body 60 isfully closed. If the air leakage amount when the valve body 60 is fullyclosed is large, increase in an idling RPM of an engine anddeterioration in fuel efficiency may result. Therefore, it is preferableto reduce the air leakage amount in the fully closed state and to reducethe engine idling RPM, thereby achieving an improvement in terms of fuelefficiency.

Embodiment 3

Embodiment 3 will be described. Like Embodiment 2, this embodiment is apartial modification of Embodiment 1.

As shown in FIG. 9, in this embodiment, annular stepped portions 74 areformed on the inner periphery of the end faces 67 of the valve member 4.Annular tubular fitting portions 75 to be fitted into the steppedportions 74 of the valve member 4 are formed on the inner periphery ofthe end faces 69 of the bearing sleeves 24.

According to this embodiment, since the tubular fitting portions 75 ofthe bearing sleeves 24 are fitted into the stepped portions 74 of thevalve member 4, the clearances 72 between the end faces of the bearingsleeves 24 and of the valve member 4 exhibit a labyrinth structure.Thus, as in Embodiment 2, it is possible to reduce the air leakageamount when the valve body 60 is fully closed.

Embodiment 4

Next, Embodiment 4 will be described. This embodiment is a partialmodification of Embodiment 1. FIG. 10 is a front sectional view of athrottle body, FIG. 11 is a sectional view of a primary portion whenmolding re the main body, FIG. 12 is an end view of a portion around abearing sleeve when molding the main body, FIG. 13 is a sectional viewof a primary portion after movement for adjustment of the bearingsleeve, FIG. 14 is an end view of a portion around the bearing sleeveafter the movement for adjustment of the bearing sleeve, FIG. 15 is asectional view of a body molding die, and FIG. 16 is a perspective viewof a bearing-sleeve pivotal die. In FIG. 10, the cover body 40, the plug26, the throttle gear 30, the back spring 32, the drive motor 33, etc.of FIG. 3 are omitted.

As is better shown in FIG. 11, in this embodiment, the bearing sleeves24 of Embodiment 1 (see FIG. 3) are replaced with straight cylindricalbearing sleeves (indicated by reference numeral 84). Like the bearingsleeves 24, the bearing sleeves 84 correspond to the “bearing members”in this specification.

As shown in FIG. 16, a male thread 85 is formed on the outer peripheralsurface of each bearing sleeve 84. Further, in the outer end face ofeach bearing sleeve 84 on a side opposite to the valve, two recesses 86are formed, for example, at radially opposing positions (see FIG. 12).

As shown in FIG. 15, a body molding die 90 of this embodiment molds themain body 3 with the valve body 60 and the pair of right and leftbearing sleeves 84 inserted. The body molding die 90 is equipped with alower die 91, which is a stationary die forming a cavity 88corresponding to the main body 3, an upper die 92, which is a movabledie and is vertically movable, and. a plurality of lateral dies 93,which are movable dies and are laterally movable. The body molding die90 is applicable to the above-mentioned manufacturing method 1 for thethrottle body 2.

A pouring gate or resin injecting gate 94 is formed between the lowerdie 91 and the lateral dies 93 and communicate with the cavity 88 fromthe lateral side. The valve member 4 in the fully closed position isplaced between the lower die 91 and the upper die 92.

Further, bearing-sleeve pivotal dies 95 are respectively arranged in theright and left lateral dies 93. The bearing-sleeve pivotal dies 95 arepositioned on the rotation axis L of the throttle shaft 20 and arerotatable and axially movable by a driving means (not shown). Engagingprojections 96 are formed on distal ends of the bearing-sleeve pivotaldies 95 are respectively engageable with the recesses 86 of the bearingsleeves 84 (see FIG. 16).

The case in which the main body 3 is molded by the body molding die 90will be described. As shown in FIG. 15, the valve body 60 is insertedinto the body molding die 90 with the valve member 4 in the fully closedstate, and the bearing sleeves 84 (see FIG. 16) are fitted with thesupport shaft portions 21 of the throttle shaft 20. In this state, thedies 91, 92, 93, 95 of the body molding die 90 are closed. At that time,the engaging projections 96 of the right and left bearing-sleeve pivotaldies 95 respectively engage with the recesses 86 of the bearing sleeves84. Subsequently, resin (more specifically, molten resin) is injectedfrom the resin injecting gate 94 into the cavity 88 defined by the bodymolding die 90 to thereby mold the main body 3.

Then, in a semi-cured state prior to the curing of the resin, the rightand left bearing-sleeve pivotal dies 95 are pivoted by a predeterminedangle (see arrow Y1 in FIG. 14), so that the bearing sleeves 84 move inthe axial direction or to threadably retreat by a predetermined amount(see arrow Y2 in FIG. 13) with respect to the bearing boss portions 22.of the main body 3 (see FIG. 14). In this specification, “semi-curedstate of the resin” means such a semi-cured state that allows thebearing sleeves 84 to move in the axial direction through rotationwithout generating any cracks in the bearing boss portions 22 of themain body 3 and that does not cause accidental flow of resin intoclearances 98 set between the valve member 4 and the bearing sleeves 84by the movement of the bearing sleeves 84. This semi-cured state of theresin also corresponds to the state “after molding the main body” inthis specification.

As a result, predetermined clearances 98 are ensured between the endfaces 67 of the valve member 4 and the end faces 69 of the bearingsleeves 84 (see FIG. 13). The threadably retreating amount (axialretreating amount) of the bearing sleeves 84 at this time is such anamount that takes into account of the molding shrinkage of the main body3 and that ensures the predetermined clearances 98 (see FIG. 13) betweenthe end faces 67 of the valve member 4 and the end faces 69 of thebearing sleeves 84.

After completion of the curing of the main body 3, the dies 91, 92, 93,95 are opened, and the mold product or the throttle body 2 (see FIG. 10)is extracted.

According to the throttle body 2 described above, after molding the mainbody 3 (in the semi-cured state prior to the curing of the resin in thisembodiment), the bearing sleeves 24 provided on the main body 3 aremoved in the axial direction of the throttle shaft 20, so that theclearances 98 (see FIG. 13) between the end faces 67 of the valve member4 and the end faces 69 of the bearing sleeves 24 are adjusted to apredetermined amount. Thus, it is possible to improve the operationproperty of the valve body 60.

If the clearances 98 is too large, the air leakage amount in the fullyclosed state increases. Therefore, the bearing sleeves 84 are moved inthe axial direction of the throttle shaft 20 with respect to the mainbody 3 in order to provide the clearances 98 (see FIG. 13) between theend faces 67 of the valve member 4 and the end faces 69 of the bearingsleeves 24, which clearances enable to reduce the air leakage amount inthe fully closed state of the valve member 4 while improving theoperation property of the valve member 4.

Conventionally, when molding the main body 3, predetermined clearancesare ensured between the valve member 4 and the bearing members (straightcylindrical bearings without male threads) by taking into account of themolding shrinkage of the main body 3 beforehand, and the main body 3 ismolded in this state. Therefore, the resin may flow into the clearancesto fill the requisite clearances to impair the operation property of thevalve body 60.

In contrast, according to the present embodiment, it is possible, asdescribed above, to ensure the requisite clearances 98 (see FIG. 13)between the valve member 4 and the bearing sleeves 84, so that it ispossible to improve the operation property of the valve body 60.

According to the above-mentioned manufacturing method for the throttlebody 2, it is possible to manufacture a throttle body 2 that can providethe above-mentioned effects.

Embodiment 5

Next, Embodiment 5 will be described. This embodiment is a partialmodification of Embodiment 1. FIG. 17 is a sectional view of a primaryportion, and FIG. 18 is a perspective view of a spacer member.

This embodiment is applicable to the manufacturing method 1 ormanufacturing method 2 for the throttle body 2 described in Embodiment1.

In the manufacturing method 1 for the throttle body 2, when molding themain body 3 with the valve member 4 inserted together with the bearingsleeves 24, ring-plate-like spacer members 114 having a predeterminedthickness 114 t (see FIG. 18) are positioned between the end faces 67 ofthe valve member 4 and the end faces 69 of the bearing sleeves 24 (seeFIG. 17).

In the manufacturing method 2 for the throttle body 2, when molding thevalve member 4 with the main body 3 inserted together with the bearingsleeves 24, the ring-plate-like spacer members 114 having thepredetermined thickness 114 t (see FIG. 18) are positioned between theend faces 67 of the valve member 4 and the end faces 69 of the bearingsleeves 24 (see FIG. 17). In this case, until the valve member 4 ismolded, the end faces of the valve molding die (not shown) defining thesame planes as the end faces 67 of the valve member 4 (hereinafterreferred to as end faces of the valve member 4) correspond to the “endfaces 67 of the valve member 4”, and the spacers members 114 arepositioned between those end faces and the end faces 69 of the bearingsleeves 24.

The spacer members 114 are made of a material, such as bismuth, which ismelted by the heat of hot water, an easily meltable alloy containingtin, etc., or a medicinal wafer, which is melted in water, and aresolved by a dissolving means, such as chemical products, water, hotWater, or high temperature atmosphere. The spacer members 114 correspondto the “spacer means” in this specification.

As described above, by positioning the spacer members 114 (see FIG. 18)between the end faces 67 of the valve member 4 and the end faces 69 ofthe bearing sleeves 24, it is possible to mold the main body 3 or thevalve member 4, with clearances (indicated by the same reference numeralas the thickness) 114 t corresponding to the thickness 114 t of thespacer members 114 ensured between the end faces 67 and 69. In addition,due to the presence of the spacer members 114, it is possible to preventor reduce accidental flow of the resin between the end faces 67 of thevalve member 4 and the end faces 69 of the bearing sleeves 24 when theresin is injected. The thickness 114 t of the spacer members 114 is setto a dimension corresponding to the predetermined clearances 114 t thattakes into account of the molding shrinkage of the main body 3.

After the completion of curing of the resin of the main body 3 or thevalve member 4, the spacer members 114 are dissolved and removed, forexample, by the dissolving means as described above, so that it ispossible to form the predetermined clearances 114 t (see FIG. 17)between the valve member 4 and the bearing sleeves 24 and to ensure therequisite operation property of the valve member 4.

Further, since there the clearances between the end faces 67 of thevalve member 4 and the end faces 69 of the bearing sleeves 24 will notbecome greater than a predetermined value, it is possible to prevent orreduce accidental inflow of the resin into the clearances 114 t duringmolding, and increase in air leakage amount when the valve member 4 isin the fully closed state.

Further, as described above, due to the use of the spacer members 114that are dissolved by the dissolving means, it is possible, in themanufacturing method 1 for the throttle body 2, to set the clearances114 t between the end faces 67 of the valve member 4 and the end faces69 of the bearing sleeves 24 by using the end faces 67 of the valvemember 4 as a reference. In the manufacturing method 2 for the throttlebody 2, it is possible to set the clearances 114 t between the end faces67 of the valve member 4 and the end faces 69 of the bearing sleeves 24by using the end faces 69 of the bearing sleeves 24 as a reference.

With the throttle body 2 described above, when molding one of the valvebody 60 and the main body 3 with the other inserted together with thebearing sleeves 24, the spacer members 114 are positioned between theend faces 67 of the valve member 4 and the end faces 69 of the bearingsleeves 24, and the spacer members 114 are removed after molding themain body 3 or the valve member 4. Therefore, it is possible to setpredetermined clearances 114 t between the end faces 67 of the valvemember 4 and the end faces 69 of the bearing sleeves 24 by the spacermembers 114, so that operation property of the valve body 60 can beimproved. Further, the clearances 114 t between the end faces 67 of thevalve member 4 and the end faces 69 of the bearing sleeves 24 are thoseenabling reduction of the air leakage amount when the valve body 60 isfully closed while improving the operation property of the valve body60. Therefore, it is possible to reduce the air leakage amount when thevalve body 60 is fully closed while improving the operation property ofthe valve body 60.

According to the above-mentioned manufacturing method for the throttlebody 2, it is possible to manufacture a throttle body 2 providing theabove-mentioned effects.

The following modifications 1 through 5 may be considered for Embodiment5.

Modification 1

As shown in FIG. 19, between the end faces 67 of the valve member 4 andthe end faces 69 of the bearing sleeves 24, pairs of metal gage members117 having half-ring-plate-like configurations and having apredetermined thickness 117 t (see FIG. 20) are positioned in place ofthe spacer members 114 (see FIG. 17). The gage members 17 are formed,for example, of clearance gages, and are removed by a mechanicalexternal force after the resin of the main body 3 or the valve member 4has been cured. Therefore, it is possible to form predeterminedclearances (clearances corresponding to the thickness 117 t) between theend faces 67 of the valve member 4 and the end faces 69 of the bearingsleeves 24. The gage members 117 correspond to the “spacer means” inthis specification.

Modification 2

As shown in FIG. 21, projection portions 118 adapted to contact with theend faces 69 of the bearing sleeves 24 for ensuring predeterminedclearances are integrally provided on the end faces 67 of the valvemember 4 (see FIG. 22). After the resin of the main body 3 or the valvemember 4 has been cured, the projection portions 118 of the valve member4 are removed by a removing means, such as snapping or cutting, so thatit is possible to form predetermined clearances (clearancescorresponding to the projecting amount of the projection portions 118)between the end faces 67 of the valve member 4 and the end faces 69 ofthe bearing sleeves 24. The projection portions 118 correspond to the“spacer means” in this specification.

In Modification 2, it is also possible to provide the projectionportions 118 on the end faces 69 of the bearing sleeves 24 such that itcan contact with the end faces 67 of the valve member 4, or to providethem on the molding die for the valve body 60 such that they can contactwith the end faces 69 of the bearing sleeves 24. Therefore,predetermined clearances between the end faces 67 of the valve member 4and the end faces 69 of the bearing sleeves 24 can be ensured. Also inthis case, the projection portions 118 are removed by a removing means,such as snapping, cutting, or laser, after the main body 3 or the valvemember 4 has been molded.

Modification 3

As shown in FIG. 23, projecting portions 215 each having a contactingend face 215 a for ensuring predetermined clearances by contacting withthe end faces 69 of the bearing sleeves 24 are integrally formed on theplate-like portions 63 of the valve member 4. The projecting portions215 protrude beyond the end faces 67 of the valve member 4 by an amountcorresponding to the predetermined clearances. After the resin of themain body 3 or the valve member 4 has been cured, the projectingportions 215 of the valve member 4 are removed by a removing means, suchas laser, in order to form end surfaces 67 defining the same planes asthe end faces 67 on the plate-like portions 63 of the valve member 4(see FIG. 24), so that it is possible to form predetermined clearances(indicated by reference numeral 217 in FIG. 29) between the end faces 67of the valve member 4 and the end faces 69 of the bearing sleeves 24.The projecting portions 215 correspond to the “spacer means” in thisspecification.

The projecting portions 215 of Modification 3 may be provided on the endfaces 69 of the bearing sleeves 24 such that they can contact with theend faces 67 of the valve member 4, or they may be provided on themolding die for the valve member 4 such that they can contact with theend faces 69 of the bearing sleeves 24. Therefore, it is possible toensure predetermined clearances between the end faces 67 of the valvemember 4 and the end faces 69 of the bearing sleeves 24. Also in thiscase, the projecting portions 215 are removed by a removing means, suchas laser, after the main body 3 or the valve body 60 has been molded.

Modification 4

As shown in FIG. 25, between the end faces 67 of the valve member 4 andthe end faces 69 of the bearing sleeves 24, rubber resilient members 116of substantially the same configuration as the spacer members 114 ofEmbodiment 5 (see FIG. 18) are positioned. Like the spacer members 114of Embodiment 5, the resilient members 116 are removed by a removingmeans after curing of the resin of the main body 3 or the valve member4, so that it is possible to set predetermined clearances 116 t of apredetermined amount between the end faces 67 of the valve member 4 andthe end faces 69 of the bearing sleeves 24. The resilient members 116correspond to the “spacer means” in this specification.

Further, it is possible to regard ranges allowed for resilientdeformation (compressive deformation) in the thickness direction of theresilient members 116 as the clearances between the end faces 67 of thevalve member 4 and the end faces 69 of the bearing sleeves 24. In thiscase, there is no need to remove the resilient members 116 after theresin of the main body 3 or the valve member 4 has been cured.

By integrally forming the resilient members 116 on the end faces 67 ofthe valve member 4 or the end faces 69 of the bearing sleeves 24 inadvance by two-color molding, it is advantageously possible to omit thetime and effort for mounting the resilient members 116.

As a material of the resilient members 116, it is possible, for example,to use elastomer.

The present invention is not restricted to the above-mentionedembodiments and allows modifications without departing from the gist ofthe present invention.

1. A throttle body comprising: a resin main body defining a bore throughwhich intake air flows; and a valve body having a shaft part rotatablysupported by the main body via bearing members and a resin valve partfor opening and closing the bore of the main body, end faces of thevalve part slidably contacting with end faces of the bearing members,wherein: the end faces of at least one of the valve part and the bearingmembers slidably contacting with each other are formed as end faces of agood sliding property, and the end faces of the bearing members areformed to have a radius equal to or larger than a radius of paths ofrotation of radially outer ends of the end faces of the valve part.
 2. Athrottle body according to claim 1, wherein the bearing members are madeof material having a good sliding property.
 3. A throttle body accordingto claim 1, wherein slide layers having a good sliding property areprovided on the end faces of the bearing members, which slidably contactwith the end faces of the valve part.
 4. A throttle body according toclaim 1, wherein the slide layers having a good sliding property areprovided on the end faces of the valve part, which slidably contact withthe end faces of the bearing members.
 5. A throttle body according toclaim 1, wherein the slide layers having a good sliding property areprovided on outer peripheral surfaces of support shaft portions of theshaft part, which are rotatably supported by the bearing members.
 6. Athrottle body according to claim 1, wherein the slide layers having agood sliding property are provided on inner peripheral surfaces of shaftholes of the bearing members, which rotatably support the shaft part. 7.A throttle body comprising: a resin main body defining a bore throughwhich intake air flows; and a valve body having a shaft part rotatablysupported by the main body via a pair of bearing members and a resinvalve part for opening and closing the bore of the main body, end facesof the valve part slidably contacting with end faces of the bearingmember, wherein: the bearing members are made of metal, the shaft partis made of resin, and slide layers having a good sliding property areprovided on outer peripheral surfaces of support shaft portions of theshaft part, which are rotatably supported by the bearing members.
 8. Athrottle body comprising: a resin main body defining a bore throughwhich intake air flows; and a valve body having a shaft part rotatablysupported by the main body via a pair of bearing members and a resinvalve part for opening and closing the bore of the main body, end facesof the valve part slidably contacting with end faces of the bearingmember, wherein: the bearing members are made of resin, the shaft partis made of metal, and slide layers having a good sliding property areprovided on the end faces of the valve part, which slidably contact withthe end faces of the bearing members.
 9. A throttle body comprising: aresin main body defining a bore through which intake air flows; and avalve body having a shaft part rotatably supported by the main body viaa pair of bearing members and a resin valve part for opening and closingthe bore of the main body, end faces of the valve part slidablycontacting with end faces of the bearing member, wherein: the bearingmembers are made of resin, the shaft part is made of metal, and slidelayers having a good sliding property are provided on the end faces ofthe bearing members, which slidably contact with the end faces of thevalve part.
 10. A throttle body comprising: a resin main body defining abore through which intake air flows; and a valve body having a shaftpart rotatably supported by the main body via a pair of bearing membersand a resin valve part for opening and closing the bore of the mainbody, end faces of the valve part slidably contacting with end faces ofthe bearing members, wherein: the bearing members and the shaft part aremade of a resin, and slide layers having a good sliding property areprovided on the end faces of the valve part slidably contacting with theend faces of the bearing members and on outer peripheral surfaces ofsupport shaft portions of the shaft part, which are rotatably supportedby the bearing members.
 11. A throttle body comprising: a resin mainbody defining a bore through which intake air flows; and a valve bodyhaving a shaft part rotatably supported by the main body via a pair ofbearing members and a resin valve part for opening and closing the boreof the main body, end faces of the valve part slidably contacting withend faces of the bearing members, wherein: the bearing members are madeof resin, the shaft part is made of metal, and slide layers having agood sliding property are provided on the end faces of the bearingmembers slidably contacting with the end faces of the valve part and oninner peripheral surfaces of shaft holes of the bearing members, whichrotatably support the shaft part.
 12. A throttle body comprising: aresin main body defining a bore through which intake air flows; and avalve body having a shaft part rotatably supported by the main body viaa pair of bearing members and a resin valve part for opening and closingthe bore of the main body, end faces of the valve part slidablycontacting with end faces of the bearing members, wherein clearancesbetween the end faces of the valve part and the end faces of the bearingmembers are adjusted through axial movement of the bearing members. 13.A throttle body comprising: a resin main body defining a bore throughwhich intake air flows; and a valve body having a shaft part rotatablysupported by the main body via a pair of bearing members and a resinvalve part for opening and closing the bore of the main body, end facesof the valve part slidably contacting with end faces of the bearingmembers, wherein, between the end faces of the valve part and the endfaces of the bearing members, spacer means for setting clearancesbetween the end faces to a predetermined amount are provided.
 14. Amethod of manufacturing a throttle body, the throttle body comprising: aresin main body defining a bore through which intake air flows; and avalve body having a shaft part rotatably supported by the main body viaa pair of bearing members and a resin valve part for opening and closingthe bore of the main body, end faces of the valve part slidablycontacting with end faces of the bearing members, the method ofmanufacturing the throttle body comprising adjusting clearances betweenthe end faces of the valve part and the end faces of the bearing membersthrough axial movement of the bearing members after molding the mainbody,
 15. A method of manufacturing a throttle body, the throttle bodycomprising: a resin main body defining a bore through which intake airflows; and a valve body having a shaft part rotatably supported by themain body via a pair of bearing members and a resin valve part foropening and closing the bore of the main body, end faces of the valvepart slidably contacting with end faces of the bearing members, themethod of manufacturing the throttle body comprising setting clearancesbetween the end faces of the valve part and the end faces of the bearingmembers to a predetermined amount by spacer means when molding one ofthe valve part and the main body with the other inserted together withthe bearing members.